Brake fluid pressure control device for vehicles

Abstract

A brake fluid pressure control device for vehicles is provided capable of adjusting with a simple control a brake fluid pressure applied to a wheel brake. The control device includes for each system of an X-pipe arrangement: a cut valve as a linear solenoid valve provided to a first fluid pressure path; a pump capable of pressurizing brake fluid on a side toward the wheel brakes than the cut valve on the first fluid pressure path; and a control valve provided on the second fluid pressure path. The control device further includes: a target fluid pressure setting portion for setting a target fluid pressure for each of the wheel brake; and a valve actuating portion for drive-controlling the cut valve and the control valve, based on the target fluid pressure. The valve actuating portion performs for each of the systems the operations of drive-controlling the cut valve by using a higher one of the target fluid pressures of the wheel brakes as a target fluid pressure of the first fluid pressure path, to control the wheel brake having the higher target fluid pressure by driving only the cut valve, and of controlling a wheel brake having a lower target fluid pressure by driving the control valve corresponding to the wheel brake having the lower target fluid pressure.

1. A brake fluid pressure control device for vehicles having an X-pipe arrangement, which includes:
 a first system connecting front left and rear right wheel brakes; and 
 a second system connecting front right and rear left wheel brakes, 
 wherein each of the first and second systems includes 
 a first fluid pressure path connected to fluid pressure supply means and 
 a second fluid pressure path, 
 the first fluid pressure path being connected via the second fluid pressure path to each of the wheel brakes of the first and second systems, and controls a brake fluid pressure of each of the wheel brakes to a respective target fluid pressure, and 
 wherein the brake fluid pressure control device for vehicles comprises in each of the systems of the X-pipe arrangement: 
 a linear solenoid valve provided to the first fluid pressure path, wherein
 the linear solenoid valve comprises a valve seat and a valve body for providing a valve opening for brake fluid to flow when a separation is present between the valve seat and the valve body, and a moveable core to apply a thrust to the valve body for closing the separation, and 
 
 the linear solenoid valve adjusts a valve opening pressure, at which the separation occurs, by controlling a level of electric current provided to an electro-magnetic coil of the linear solenoid valve, the level of electric current being selected from a plurality of levels of electric current; 
 a pump, capable of pressurizing a brake fluid, communicating with the first fluid path on a side of the linear solenoid valve toward the wheel brakes; 
 a motor for driving the pump; and 
 a valve control means associated with each wheel brake, provided on the second fluid pressure path, and 
 the brake fluid pressure control device for vehicles further comprises: 
 a target fluid pressure setting portion for setting a target fluid pressure for each of the wheel brakes; and 
 a valve actuating portion for drive-controlling the linear solenoid valve and the valve control means, based on the target fluid pressure, wherein 
 the linear solenoid valve is drive-controlled by increasing and decreasing the level of current provided to the electro-magnetic coil to cause the thrust to increase and decrease respectively, and 
 the valve actuating portion performs, in each of the systems, the operations of drive -controlling the linear solenoid valve by using a higher one of the target fluid pressures of the wheel brakes as a target fluid pressure of the first fluid pressure path, to control a brake fluid pressure of the wheel brake having the higher target fluid pressure by driving only the linear solenoid valve, and of controlling a brake fluid pressure of a wheel brake having a lower target fluid pressure by driving the valve control means corresponding to the wheel brake having the lower target fluid pressure, wherein 
 when the pump pressurizes the brake fluid, the valve actuating portion performs in each of the systems the operation of driving the linear solenoid valve so that the larger the number of the brakes to be pressure-adjusted, the larger the amount of brake fluid to be returned from the linear solenoid valve to the side of the fluid pressure supply means, for a same target fluid pressure of the first fluid pressure path, and wherein 
 the valve actuating portion determines a basic indicator current provided to the electro -magnetic coil of the linear solenoid valve for pressure adjusting two wheels on the basis of a rotation number of the motor for driving the pump, 
 the valve actuating portion determines an indicator current provided to the electro-magnetic coil of the linear solenoid valve for pressure adjusting only one wheel, the indicator current being the basic indicator current increased by an offset current; and 
 the basic indicator current is larger for a larger rotation number of the motor for driving the pump. 
 
     
     
       2. The brake fluid pressure control device for vehicles according to  claim 1 ,
 wherein the valve drive portion is arranged to drive the linear solenoid valve so that the larger the number of the wheel brakes for pressure adjustment, the smaller the thrust to be applied to the valve body, for a same target fluid pressure of the first fluid pressure path in each of the systems, when the pump pressurizes a brake fluid pressure. 
 
     
     
       3. A brake fluid pressure control device for vehicles having an X-pipe arrangement, which includes:
 a first system connecting front left and rear right wheel brakes; and 
 a second system connecting front right and rear left wheel brakes, 
 wherein each of the first and second systems includes 
 a first fluid pressure path being connected to fluid pressure supply means and 
 a second fluid pressure path, 
 the first fluid pressure path being connected via the second fluid pressure path to each of the wheel brakes of the first and second systems, and controls a brake fluid pressure of each of the wheel brakes to a respective target fluid pressure, and 
 wherein the brake fluid pressure control device for vehicles comprises in each of the systems of the X-pipe arrangement: 
 a linear solenoid valve provided to the first fluid pressure path, wherein 
 the linear solenoid valve comprises a valve seat and a valve body for providing a valve opening for brake fluid to flow when a separation is present between the valve scat and the valve body, and a moveable core to apply a thrust to the valve body for closing the separation, and 
 the linear solenoid valve adjusts a valve opening pressure, at which the separation occurs, by controlling a level of electric current provided to an electro-magnetic coil of the linear solenoid valve, the level of electric current being selected from a plurality of levels of electric current; 
 a pump capable of pressurizing a brake fluid communicating with the first fluid pressure path on a side of the linear solenoid valve toward the wheel brakes; 
 a motor for driving the pump; 
 a valve control means provided associated with each wheel brake, on the second fluid pressure path to comprise an inlet valve, a discharge valve, and a check valve, and 
 the brake fluid pressure control device for vehicles further comprises: 
 a target fluid pressure setting portion for setting a target fluid pressure for each of the wheel brakes; and 
 a valve actuating portion for drive-controlling the linear solenoid valve and the valve control means, based on the target fluid pressure, wherein 
 the linear solenoid valve is drive-controlled by increasing and decreasing the level of current provided to the electro-magnetic coil to cause the thrust to increase and decrease respectively, and 
 the valve actuating portion performs, in each of the systems, the operations of drive -controlling the linear solenoid valve by using a higher one of the target fluid pressures of the wheel brakes as a target fluid pressure of the first fluid pressure path, to control a brake fluid pressure of the wheel brake having the higher target fluid pressure by driving only the linear solenoid valve, and of controlling a brake fluid pressure of a wheel brake having a lower target fluid pressure by driving the valve control means corresponding to the wheel brake having the lower target fluid pressure, wherein 
 the valve drive portion is arranged to drive the linear solenoid valve so that the larger the number of the wheel brakes for pressure adjustment, the smaller the thrust to be applied to the valve body, for a same target fluid pressure of the first fluid pressure path in each of the systems, when the pump pressurizes a brake fluid pressure, 
 the valve actuating portion determines a basic indicator current provided to the electro -magnetic coil of the linear solenoid valve for pressure adjusting two wheels on the basis of a rotation number of the motor for driving the pump, 
 the valve actuating portion determines an indicator current provided to the electro-magnetic coil of the linear solenoid valve for pressure adjusting only one wheel, the indicator current being the basic indicator current increased by an offset current; and 
 the basic indicator current is larger for a larger rotation number of the motor for driving the pump. 
 
     
     
       4. A brake fluid pressure control method for vehicles having an X-pipe arrangement, which includes:
 a first system connecting front left and rear right wheel brakes; and 
 a second system connecting front right and rear left wheel brakes, 
 wherein each of the first and second systems includes: 
 a first fluid pressure path connected to fluid pressure supply means; and 
 a second fluid pressure path, 
 the first fluid pressure path being connected via the second fluid pressure path to each of the wheel brakes of the first and second systems, and controls a brake fluid pressure of each of the wheel brakes to a respective target fluid pressure, and 
 wherein the brake fluid pressure control device for vehicles comprises in each of the systems of the X-pipe arrangement: 
 a linear solenoid valve provided to the first fluid pressure path, wherein 
 the linear solenoid valve comprises a valve seat and a valve body for providing a valve opening for brake fluid to flow when a separation is present between the valve seat and the valve body, and a moveable core to apply a thrust to the valve body for closing the separation, and 
 the linear solenoid valve adjusts a valve opening pressure, at which the separation occurs, by controlling a level of electric current provided to an electro-magnetic coil of the linear solenoid valve, the level of electric current being selected from a plurality of levels of electric current; 
 the linear solenoid valve is capable of adjusting a valve opening pressure by controlling an electric conduction to the linear solenoid valve; 
 a pump capable of pressurizing a brake fluid communicating with the first fluid pressure path on a side of the linear solenoid valve toward the wheel brakes; 
 a motor for driving the pump; 
 a valve control means associated with each wheel brake, provided on the second fluid pressure path, and 
 the brake fluid pressure control device for vehicles further comprises: 
 a target fluid pressure setting portion for setting a target fluid pressure for each of the wheel brakes; and 
 a valve actuating portion for drive-controlling the linear solenoid valve and the valve control means, based on the target fluid pressure, 
 the brake fluid pressure control method comprising, 
 having the valve actuating portion performing, in each of the systems, the steps of: 
 1) drive-controlling the linear solenoid valve, by increasing and decreasing the level of current provided to the electro-magnetic coil to cause the thrust to increase and decrease respectively, and using a higher one of the target fluid pressures of the wheel brakes as a target fluid pressure of the first fluid pressure path; 
 2) controlling a brake fluid pressure of the wheel brake having the higher target fluid pressure by driving only the linear solenoid valve; 
 3) controlling a brake fluid pressure of a wheel brake having a lower target fluid pressure by driving the valve control means corresponding to the wheel brake having the lower target fluid pressure; and 
 when the pump pressurizes the brake fluid, 
 4) driving the linear solenoid valve so that the larger the number of the brakes to be pressure-adjusted, the larger the amount of brake fluid to be returned from the linear solenoid valve to the side of the fluid pressure supply means, for a same target fluid pressure of the first pressure path; 
 5) determining a basic indicator current provided to the electro-magnetic coil of the linear solenoid valve for pressure adjusting two wheels on the basis of a rotation number of the motor for driving the pump; and 
 6) determining an indicator current provided to the electro-magnetic coil of the linear solenoid valve for pressure adjusting only one wheel, the indicator current being the basic indicator current increased by an offset current; wherein 
 the basic indicator current is larger for a larger rotation number of the motor for driving the pump.